1. Field of the Invention
The present invention relates to a cartridge type gauging head for checking linear dimensions of parts, including a substantially tubular casing, a shaft partially housed in said casing and axially movable with respect to it, a feeler coupled to the shaft for contacting the part to be checked, a guide device for guiding the axial displacement of the shaft with respect to the casing, a position transducer for providing a signal depending on the mutual positions of the shaft and the casing and resilient means for urging the shaft along a measurement direction.
2. Description of the Prior Art
Cartridge heads of the type referred to hereinabove are described in Swiss Pat. No. 594874 and U.S. Pat. No. 3,434,086. In particular, U.S. Pat. No. 3,434,086 discloses a cartridge type head comprising a generally cylindrical metal shell adapted to be closed with a metal cap which may be cemented into place or otherwise affixed. The cap has a neck provided with an axial bore guiding an armature assembly. A bobbin assembly may be cemented in the metal shell or held in place by the cap and a bushing.
It is also known in the art, as disclosed in Italian Pat. No. 906.206, to guide the axial displacements of a shaft or spindle with respect to a casing by means of a bushing including a first portion fixed to the casing, a second portion matched with a small radial clearance to the spindle for axially guiding it and an intermediate portion adapted for preventing the transmission of deformations from the first to the second portion of the bushing.